This invention relates to improvements in the manufacture of draw drapes, and more particularly to a process and apparatus for making permanent pleats in the upper edge of a draw drape.
Draw drapes, as employed for decorative purposes and controllable concealment of areas or passages, generally consist of a flexible sheet structure of fabric or film having a stiffened border known as a "heading" contiguous to the upper edge. The heading accommodates means such as hooks whereby the drape can be suspended from a draw rod or equivalent rigid track mechanism capable of slideably adjusting the drape horizontally to a drawn, compactly folded state, or to its maximum extended length.
Because the drapery is intended to have a pleasing appearance, particularly in its extended state, it is provided with pleats in the heading which cause formation of uniform vertical undulations extending the height of the drape. The undulations present an appearance of depth and natural fullness which is absent in a totally flat fabric. The pleats also serve as anchor sites for the hooks which engage with the draw rod.
Pleats or pleat assemblies are generally comprised of a sharply defined fold or group of several closely spaced folds in the heading, said folds being preserved by sewing or other means. A multitude of such pleats are uniformly spaced along the heading. The size of the folds of the pleats and their spacing is generally such as to produce a pleated heading having about half the length of the initial unpleated heading. The extent of shortening of the pleated heading is a measure of the "fullness" or appearance of the drapery. A pleated draw drape having a heading contracted to 50% of the length of the same heading prior to pleating, is said to have 100% fullness. Greater contractions produce greater fullness, and lesser contractions provide proportionally less fullness.
Several well-known types of pleats are recognized, such as the pinch, box and cartridge styles, each fabricated by a specialized method and having a distinct appearance. For example, a pinch, also known as a French pleat, is made by first forming a vertically oriented loop protruding toward the face of the drape and extending the height of the heading. The loop is then sewn closed at its base and fashioned into three smaller loops or folds by gathering and shaping the protruding fabric and pushing it back toward the heading. The three folds are joined or pinched together by sewing in a direction perpendicular to the face of the drape just below the heading, forming a seam, generally called a bar tacking. Because the folds are joined laterally at one point, the appearance is that of three folds beginning at the top of the drapery, converging just below the heading, and then diverging and leading into the undulations of the body of the drape. Since the center fold is not anchored to the top of the heading, it appearss non-uniform in height, being higher at the top of the heading than at the bottom thereof.
A box pleat is made by initially forming a vertically sewn loop, as in the case of the pinch pleat. The loop is then flattened against the heading, as by pressing, and the top and bottom portions of the flattened loop are horizontally sewn to the heading. A cartridge pleat is similar to a box pleat, but instead of being flattened, the loop remains in its full, protruding configuration.
The present invention is concerned with a pleat which may be described as a straight uniform pleat. It may have 1, 2 or 3 folds within the heading, but unlike the pinch pleat described above, the folds, when 2 or 3 are employed, are not joined together, and each fold is of uniform height throughout its vertical extent from the top to the bottom of the heading.
Because of the attendant contraction in the length of the heading during pleat formation, pleats are generally made one at a time in sequential order. This causes the operation to be slow and costly, particularly when sewing or other relatively slow bonding techniques are utilized. Mechanical methods for pleat making usually involve means for forming the folds in the heading, and means for bonding the folds while held in proper position.
In the pleat-making system of U.S. Pat. No. 2,658,551, the folds of the pleat are formed by causing a group of parallel finger blades to come down upon a thermoplastic fabric positioned above a multi-bladed jig. The fingers enmesh with the blades of the jig, causing the entrapped fabric to take a folded, serpentine path between the blades of the jig and the fingers. A separate thermoplastic backing strip is placed above the folded fabric, and a flat electrode is pressed down upon the assembly. Contact of the flat electrode with the upper edges of the jig produces lines of thermoplastic bonding which preserve the fold structure. The finger blades are then removed from the top of the pleat. Although the approach of U.S. Pat. No. 2,658,551 is effective in principle, in actual practice serious problems are encountered because the thermoplastic backing strip is positioned between the flat electrode and the multi-bladed jig. In this location, the backing strip obstructs the re-positioning of the finger blades. Therefore, in each pleat-making sequence, the backing strip must be diverted away from, then returned to its normal path. This involves not only separate steps of a nature not readily amenable to automation, but creates a high probability of non-uniform alignment of the backing strip in the course of making the pleats of a single drapery. This problem is particularly aggravated by the absence of means for accurately positioning said backing strip. Another unsatisfactory aspect of the process and apparatus of U.S. Pat. No. 2,658,551 is that the drapery is positioned face down on the working surface. This causes difficulties in accurately advancing the pleated section of the fabric, especially in the case of heavy duty draperies. Although this deficiency is recognized in U.S. Pat. No. 2,658,551, and it is disclosed therein, at column 3 lines 65-70 that the positions of the parts may be reversed, such innovation would require additional features to compensate for loss of the gravity-aided positioning of the drapery in the former case.
The use of a backing strip to secure a multi-fold pleat is also disclosed in U.S. Pat. No. 3,392,890 which utilizes adhesive to achieve bonding of the backing strip to the folds of the pleat. Such method is generally slow, and produces an unusually stiff pleat which may not survive aging or cleaning or laundering operations. Although the disclosure concerns a draw drape, the insertion of hooks behind the pleats will be difficult, if not impossible because of the adhesive layer behind each pleat.
It is an object of the present invention to provide a method and apparatus for the production of straight uniform pleats in a draw drape. It is another object to provide a method and apparatus for the rapid production of straigt uniform pleats in the heading of a draw drape and capable of engaging with drapery hooks. It is a still further object of this invention to provide a method and apparatus for the accurate and rapid production of straight uniform pleats having a backing strip and being capable of engaging with drapery hooks in the heading of a draw drape positioned face up during the pleat-making process. Other objects and advantages will appear hereinafter.